Apparatus and method for processing a substrate

ABSTRACT

A lamp house is located face to face with a substrate which is transferred by a conveyer means. A dielectric barrier discharge lamp is provided in the lamp house to irradiate the substrate with ultraviolet light, while a moistened inert gas, consisting of an inert gas and water vapor, is supplied to a space between the substrate and the dielectric barrier discharge lamp from a moistened inert gas generating means. Under irradiation of ultraviolet light from the dielectric barrier discharge lamp, water vapor in the moistened inert gas is split into a reducing active member [H.] and an oxidative active member [.OH].

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Art

[0002] This invention relates to a method and an apparatus for treatingsurfaces of substrates such as of LCD panels, semiconductor wafers,magnetic storage disks and optical storage disks which are formed ofglass, semiconductor, synthetic resin, ceramics, metals or a compositematerial of these materials, and more particularly to a method and anapparatus for treating substrate surfaces by irradiation of ultravioletlight in a washing or etching stage of a fabrication process.

[0003] 2. Prior Art

[0004] For instance, a circuit pattern including transparent electrodesis formed on a TFT substrate which constitutes a transparent substrateof an LCD panel by the use of a film-forming means. In suc a substratefabrication process, surfaces of substrates are processed by washing andetching treatments. In a processing of this sort, it has been thegeneral practice to employ a wet process in which treating liquids areapplied or injected on substrate surfaces. However, recently the so-calldry processes are introduced into this field, carrying out washing andetching treatments by irradiation of ultraviolet light.

[0005] For example, Japanese Laid-Open Patent Application H5-224167discloses a method of washing glass substrates of LCD panel. In thiscase, substrates are irradiated with ultraviolet light prior to startinga wet process using a washing liquid. In this known washing method,substrate surfaces are irradiated with ultraviolet light from alow-pressure mercury lamp in a preparatory stage leading to a washingstage. By irradiation of ultraviolet light, organic substances on thesubstrate surfaces are chemically removed, and at the same timewettability of substrate surfaces is improved to have a smaller contactangle for removing inorganic contaminants efficiently when subsequentlywashed in a shower or the like. In this regard, ultraviolet light from alow-pressure mercury lamp has peaks approximately at 185 nm and 254 nmin wavelength distribution. Ultraviolet light with such wavelengthdistribution characteristics can remove organic substances which havedeposited on substrate surfaces.

[0006] The mechanism of washing off organic substances by ultravioletirradiation includes decomposition of organic substances into productsof low molecular weights by severing chemical bonds, and activation ofdecomposed products. In addition, simultaneously ozone is produced as aresult of absorption of ultraviolet light by oxygen in the air, andozone is converted into active oxygen. Therefore, through oxidativedestructive reactions with active oxygen, activated organic contaminantsare finally converted into volatile substances such as CO_(x), H₂O,NO_(x) are released into the air, that is, removed from substratesurfaces.

[0007] As mentioned hereinbefore, ultraviolet light which is irradiatedfrom a low-pressure mercury lamp has a wavelength of 185 nm on theshorter side. Therefore, of various organic compounds which havedeposited on substrate surfaces, the ultraviolet light may not be ableto decompose those compounds which have chemical bonds of strong energylike double bonds. This means that ultraviolet light of shorterwavelengths should be employed, in order to wash substrates morecompletely.

[0008] In an attempt to solve this problem, proposed in JapaneseLaid-Open Patent Specification H7-196303 is a method of dry-washingwork, irradiating substrate surfaces with vacuum ultraviolet light froma dielectric barrier discharge lamp.

[0009] In the case of this washing method according to JapaneseLaid-Open Patent Specification H7-196303, in removing organiccontaminants which have deposited on substrate surfaces, activeoxidative decomposition products are produced by chemical reaction withultraviolet light rays in vacuum. Namely, in this case, ultravioletlight rays of 172 nm which are irradiated from a dielectric barrierdischarge lamp decompose organic substances into products of lowmolecular weight by destructing chemical bonds in the organicsubstances, while at the same time activating the decompositionproducts. At the same time, oxygen in the air is decomposed andactivated by the action of the ultraviolet light. Therefore, theactivated organic substances are converted into volatile substances suchas CO_(x), H₂O, NO_(x) and so forth by oxidative reactions with activeoxygen and ultimately released into the air. As a result, the treatedsubstrate surfaces come to have a smaller contact angle in terms ofwettability.

[0010] However, since ultraviolet light is consumed for cracking oxygenin the air, an air layer between the discharge lamp and a substrate isincreased in thickness to cause an exponential attenuation to the amountof ultraviolet light rays which can reach a substrate surface.Consequently, there occur conspicuous degradations in the capacities ofactivating organic substances on substrate surfaces and producing activeoxygen in the vicinity of substrate surfaces, that is, in the capacityof removing contaminant organic substances by ultraviolet light.Besides, it is only active oxidative decomposition products that areproduced by irradiation of an oxygen-containing fluid with ultravioletlight in vacuum. Therefore, depending upon the kinds of organicsubstances which have deposited on substrate surfaces, it is often founddifficult to remove deposited organic contaminants from substratesurfaces simply by oxidative reactions.

SUMMARY OF THE INVENTION

[0011] In view of the foregoing situations, it is an object of thepresent invention to enhance the accuracy and efficiency in washing ortreating substrate surfaces with ultraviolet light rays. It is a morespecific object of the present invention to enhance decomposing effectson organic contaminant substances on substrate surfaces while at thesame time minimizing the contact angle of substrate surfaces byirradiating same with ultraviolet light in an atmosphere substantiallyfree of oxygen.

[0012] It is another object of the present invention to provide a methodand an apparatus for producing an oxidative active member and a reducingactive member by irradiating substrate surfaces with ultraviolet lightrays in a mixed atmosphere of an inert gas and, thereby ensuringreactions with decomposition products of organic substances to proceedefficiently in an assured manner.

[0013] In accordance with the present invention, for achieving theabove-stated objectives, there is provided an apparatus for treatingsubstrate surfaces, which comprises: a lamp house located over asubstrate transfer path and face to face with a treating surface of asubstrate being transferred along the transfer path by a conveyer means;a dielectric barrier discharge lamp fixedly mounted in the lamp house toirradiate ultravilot light toward the substrate; and a moistened inertgas generating means adapted to supply a water vapor-containingmoistened inert gas to a space between the substrate and the dielectricbarrier discharge lamp; producing a reducing active member [H.] and anoxidative active member [.OH] by irradiating said moistened inert gaswith ultraviolet light from said dielectric barrier discharge lamp.

[0014] The lamp house may be arranged to have an ultraviolet lighttransmitting window on the side which faces a substrate under treatment.Alternatively, in a case where the lamp house is provided within achamber, it may be opened to the chamber on the side which faces asubstrate. In such a case, an inert gas feed means is connected to thelamp house to put the latter in an inert gas atmosphere. The chamber isput in a moistened inert gas atmosphere which is substantially free ofoxygen, between entrance and exit openings which are provided atupstream and downstream ends for substrates to be treated.Alternatively, the lamp house may left open on the side of the chamber,or may be fitted with such a partition member on the open side as willtransmit ultraviolt light and contain a large number of passages to letthe inert gas flow out.

[0015] In another form of the present invention, the lamp house islocated in and opned to the chamber, and an inert gas feed means isconnected to the lamp house. Further, the moistened inert gas generatingmeans may be arranged to include a moistened inert gas feed means whichis connected to the chamber to supply a water vapor-containing moistenedinert gas toward the surface of a substrate.

[0016] Alternatively, the moistened inert gas generating means may beconstituted by a pure water vessel which is located within the chamberwith an upper open end face to face with the lamp house across thesubstrate transfer path, and an inert gas feed means which is providedwith blow holes to blow an inert gas into the pure water vessel.

[0017] On the other hand, according to the present invention, there isalso provided a method for treating substrate surfaces, which comprisesthe steps of: placing a substrate in a mixed atmosphere of an inert gasand water vapor under irradiation of ultraviolet light from a dielectricbarrier discharge lamp, thereby splitting water vapor into a reducingactive member [H.] and an oxidative active member [.OH]; and letting thereducing and oxidative active members [H.] and [.OH] contact with asurface of said substrate to be treated.

[0018] According to a more specific form of the present invention, themethod for treating substrate surfaces comprises the steps of:horizontally transferring a substrate into a mixed atmosphere of aninert gas and water vapor under irradiation of ultraviolet light from adielectric barrier discharge lamp, thereby decomposing organicsubstances deposited on a surface of the substrate and at the same timesplitting water vapor into a reducing active member [H.] and anoxidative active member [.OH]; dry-washing and minimizing contact angleof a surface of the substrate by subjecting the reducing and oxidativeactive members [H.] and [.OH] to reactions with decomposition productsof the organic substances; wet-washing the substrate by supplying a washliquid thereto; and drying the substrate.

[0019] The above and other objects, features and advantages of thepresent invention will become apparent from the following particulardescription of the invention, taken in conjunction with the accompanyingdrawings. Needless to say, the accompanying drawings show by way ofexample some preferred embodiments of the present invention forillustrative purposes only, and should not be construed as beinglimitative of the invention in any way whatsoever.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In the accompanying drawings:

[0021]FIG. 1 is a schematic view of a dielectric barrier discharge lampassembly used on a substrate processing apparatus according to thepresent invention;

[0022]FIG. 2 is a fragmentary enlarged view of the dielectric barrierdischarge lamp assembly shown in FIG. 1;

[0023]FIG. 3 is a schematic sectional view of a substrate processingapparatus, adopted as a first embodiment of the present invention;

[0024]FIG. 4 is a diagrammatic view of an inert gas moisturizer;

[0025]FIG. 5 is a schematic view of a substrate processing apparatus,adopted as a second embodiment of the present invention;

[0026]FIG. 6 is a graph, showing results of wettability improving testsusing various supply gases to substrates, which were irradiated withultraviolet light in a standstill state;

[0027]FIG. 7 is a schematic sectional view of a substrate processingapparatus, adopted as a third embodiment of the present invention;

[0028]FIG. 8 is a schematic sectional view of a substrate processingapparatus, adopted as a fifth embodiment of the present invention;

[0029]FIG. 9 is a schematic sectional view of a substrate processingapparatus, adopted as a sixth embodiment of the present invention;

[0030]FIG. 10 is a schematic sectional view of a substrate processingapparatus, adopted as a seventh embodiment of the present invention;

[0031]FIG. 11 is a schematic sectional view of a substrate processingapparatus, adopted as a eighth embodiment of the present invention; and

[0032]FIG. 12 is a schematic illustration of a substrate washing anddrying line including a drying washing stage.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0033] Hereafter, the present invention is described more particularlyby way of its preferred embodiments shown in the drawings. Firstly,schematically shown in FIGS. 1 and 2 is a dielectric barrier dischargelamp assembly (hereinafter referred to simply as ‘discharge lamp’ forbrevity) which is employed on substrate processing apparatus accordingto the present invention.

[0034] In these figures, indicated at 1 is the discharge lamp. Thedischarge lamp 1 is constituted by a quartz glass tube 4 of an annularshape, having inner and outer tubes 2 and 3 which are both formed ofquartz glass and integrally with each other. Provided internally of thequartz glass tube 4 is a hermetically closed discharge space 5. Securelyfixed to the inner side of the inner tube 2 is a metal electrode 6consisting of a cylindrical metal sheet. On the other hand, provided onthe outer periphery of the outer tube 3 is a metal mesh electrode 7. Anac power source 7 is connected between the metal electrode 6 and metalmesh electrode 6. Further, a passage for a cooling fluid 11 (e.g.,cooling water) is provided on the inner side of the inner tube 2 forcooling the metal electrode 6.

[0035] A discharge gas is sealed in the quartz glass tube 4, so that,upon applying an ac high voltage between the metal electrode 6 and themetal mesh electrode 7, discharge plasma (dielectric barrier discharge)occurs across a dielectric between the inner and outer tubes 2 and 3,and, by this discharge plasma, atoms of the discharge gas are excitedinto a plasma discharge state. Plasma discharge emission takes place asthe discharge gas atoms in the plasma state return to a normal state. Atthis time, the emission spectrum varies depending upon the nature of thedischarge gas which is sealed in the quartz glass tube 4. In the case ofa xenon (Xe) gas, for example, monochrome light having a centerwavelength at 172 nm is emitted. In a case where argon (Ar) gas is usedas a discharge gas, the emission has a center wavelength of 126 nm whichis shorter than that of a low-pressure mercury lamp. The metal electrode6 functions as a reflector plate, while the metal mesh electrode 7functions substantially as a transparent electrode. Therefore,ultraviolet light of short wavelength is irradiated from the side of theouter tube 3. In this instance, for example, the charged pressure ofxenon gas is approximately 350 torr.

[0036] Schematically illustrated in FIG. 3 is an apparatus fordry-washing transparent substrates of LCD panels by the use of thedischarge lamp 1 as described above. In this figure, indicated at 10 isa substrate plate under a dry-washing treatment. For example, thesubstrate 10 consists of a thin plate of glass, semiconductor, syntheticresin, ceramics, metal and so forth, and of a rectangular or circularshape in plan view. The substrate 10 is supported on a transfer means,for example, on a roller conveyer 11 and thereby transferred in thedirection indicated by an arrow in the same figure while receiving adry-washing treatment on its surface or surfaces. For this purpose, alamp house 12 of the washing apparatus is located in a predeterminedposition in the path of transfer by the roller conveyer 11. The lamphouse 12 is so positioned as to face the surface or surfaces of thesubstrate 10 which need a treatment.

[0037] The lamp house 12 is in the form of an enclosure or a containerwhich is open on the lower side, and is internally provided with one ora plural number of discharge lamps 1 (three discharge lamps in the caseof the particular embodiment shown). In this instance, the lower end ofthe lamp house 12 is positioned to face the upper surface of thesubstrate 10 in non-contacting state with the latter, more particularly,is maintained in small gap relation with the upper surface of thesubstrate 10 by adjusting a substrate transfer level by the rollerconveyer 12. Connected to the lamp house 12 is a nitrogen gas feed pipe13 which supplies the lamp house 12 with nitrogen gas (N₂ gas) as aninert gas in a dry state. Namely, the lamp house 12 is supplied with adry nitrogen gas under a predetermined pressure to maintain the insideof the lamp house in an atmosphere free of oxygen. This arrangementsprevent ultraviolet light from the discharge lamp 1 from attenuatingbefore reaching a proximity of the treating surface of the substrate 10.

[0038] Indicated at 14 is a chamber for a dry-washing treatment, and thelower end of the lamp house 12 is opened to the chamber 14, whichcontains the lower side of the roller conveyer 11. Connected to thechamber 14 is a moistened inert gas feed pipe 15 which supplies thechamber 14 with a moistened inert gas, which is a mixed fluid of watervapor and nitrogen gas. The moistened inert gas is supplied underpressure which is slightly lower than the pressure of nitrogen gas whichis supplied to the lamp house 12. Therefore, although the lower end ofthe lamp house 12 is opened to the chamber 14, the moistened inert gaswould not go into the lamp house 12.

[0039] Further, the chamber 14 is provided with an entrance opening 14 aat one end for admission of a substrate 10 and with an exit opening 14 bat the other end for a substrate leaving the chamber 14. In order toprevent the nitrogen gas and the moistened inert gas from escapingthrough the entrance and exit openings 14 a and 14 b, the chamber 14 isprovided with pressure chambers 15 at its opposite ends, that is, on theouter side of the entrance and exit openings 14 a and 14 b,respectively. By compressed air which is supplied through pipes 17, thepressures in these pressure chambers 16 are maintained at a level whichis slightly higher than the internal pressure of the chamber 14.Further, an exhaust pipe 18 is connected to the chamber 14, forciblydischarge exhaust gases therethrough to maintain the inside of thechamber 14 constantly at a predetermined pressure level.

[0040] Alternatively, instead of supplying compressed air, the pressurechambers 16 may be maintained at a negative pressure level by applyingsuction force to the pipes 17. In case the pressure chambers 16 aremaintained at a negative pressure level, gases in the chamber 14 flowinto the pressure chambers 16 through the entrance and exit openings 14a and 14 b. Therefore, in this case, the pressure chambers 16 and pipes17 function as an exhaust means, and it becomes unnecessary to connectthe exhaust pipe 18 to the chamber 14.

[0041] The moistened inert gas feed pipe 15, which supplies a mixture ofnitrogen gas and steam, is connected to an inert gas moisturizer, whichis arranged, for example, as shown in FIG. 4. In this figure, indicatedat 20 is a nitrogen gas tank as a source of nitrogen gas. A feed pipe 21from the nitrogen gas tank 20 is divided into two branch pipes 21 a and21 b, of which the branch pipe 21 a is connecting to a mixing container24 through a flow regulator valve 22 and a flow meter 23.

[0042] On the other hand, the branch pipe 21 b is connected to andsubmerged in a pure water tank 27 through a flow regulator valve 25 anda flow meter 26. A submerged portion of the branch pipe 21 b in the purewater tank 27 is provided with a multitude of fine pores for blowing outnitrogen gas. Therefore, nitrogen gas, which is supplied into the purewater tank 27 through the branch pipe 21 b under a predeterminedpressure, climbs up in the form of bubbles toward the water surface,generating water vapor on the way. As a result, nitrogen gas ismoistened with water vapor, forming a moistened nitrogen gas which canserves as a moistened inert gas. The thus-formed moistened nitrogen gasis introduced into the mixing container 24 through a pipe 28, and mixedwith nitrogen gas from the branch pipe 21 a to adjust the water vaporconcentration in the moistened inert gas. Through a pressure regulatorvalve 29, the moistened inert gas is supplied from the mixing container24 to the moistened inert gas feed pipe 15 which is connected to thechamber 14 as described hereinbefore. Thus, the moistened nitrogen gaspressure in the chamber 14 can be adjusted by way of the pressureregulator valve 29.

[0043] With the arrangements arranged as described above, dry nitrogengas is fed to the lamp house 12 of the processing apparatus having thedischarge lamp 1 lit on, while moistened nitrogen gas filled in thechamber 14 to provide an atmosphere substantially free of oxygen. Inthis state, a substrate 10 on the roller conveyer 11 (having a pluralnumber of rollers mounted on rotational shafts at predeterminedintervals in the substrate transfer direction) is fed into the chamber14 through the entrance opening 14 a and passed through the chamber 14under the lamp house 12 at a predetermined speed. While passing throughthe chamber 14, the surface of the substrate 10 is irradiated with shortwavelength ultraviolet light from the discharge lamp 1 for dry-washingand improving wettability of the substrate surface.

[0044] At this time, a mixed fluid of nitrogen gas and water exists onor in the vicinity of the substrate surface, and water is cracked underirradiation of ultraviolet light from the discharge lamp 1 into areducing active member [H.] and an oxidative active member [.OH].Accordingly, by irradiation of short wavelength ultraviolet light,organic contaminants which have deposited on the surface of thesubstrate 10 are decomposed into products of lower molecular weights.Further, the low molecular weight products resulting from thedecomposition of organic contaminants are subjected to reducing andoxidative reactions with the cracked active members of water. Morespecifically, not only oxidative reactions with the oxidative activemember [.OH] but also reducing reactions with reducing active member[H.] take place on or in the vicinity of the surface of the substrate 10to convert decomposed organic substances into volatile substancesquickly in a more assured manner, and the resulting volatile substancesare released to the outside through the exhaust pipe 18. As a result ofthis dry washing treatment, organic contaminants are removed from thesurface of the substrate 10. Besides, the substrate surface becomes tohave a smaller contact angle as a result of irradiation of shortwavelength ultraviolet light in the presence of water vapor.

[0045] In this manner, the substrate surface with a smaller contactangle shows improved wettability in a subsequent wet washing treatmentin a shower, permitting to wash away organic contaminants readily andcompletely from its surfaces. Accordingly, the substrate 10 can bewashed into an extremely clean state. The above-described dry-washingtreatment may be carried out for the purpose of improving surfaceconditions of substrates in a stage preparatory to application of aliquid developer or the like.

[0046] In the case of the first embodiment described above, the lamphouse is connected to the lower chamber. However, for the sake ofsimplification in construction, it may be arranged, for example, asshown in FIG. 5. In the embodiment of FIG. 5, a lamp house 112 isarranged to completely cover or enshroud discharge lamps 1. In thiscase, on the side which faces a substrate 10, the lamp house 112 isprovided is with a window 112 a which is fitted with a pane of glasswhich is highly transmissive of ultraviolet light, such as syntheticquartz glass or the like. With the lamp house 112 of this construction,the inert gas is sealed in the lamp house 112 and not allowed to escapeto the outside. Accordingly, in this case, there is no necessity forconstantly feeding an inert gas to the lamp house 112 as long as apredetermined amount of inert gas is sealed therein.

[0047] Shown in FIG. 6 are results of wettability improving experimentsusing the apparatus of FIG. 5 and changing the nature of a feed gas tothe substrate 10.

[0048] In the experiments, dry air, moistened air containing watervapor, dry nitrogen gas and moistened nitrogen gas containing watervapor were used as a feed gas. The apparatus of FIG. 4 was used formoistened air and for moistened nitrogen gas, preparing a moistened gasby connecting to a pure water tank a pipe of 5 mm in inside diameterhaving 10 pores of 1 mm in diameter in its submerged fore end portions.Produced moistened gas was mixed with a dry gas in a ratio of 1:1. Whena substrate 10 came to a position under the lamp house 12, the rollerconveyer 11 was stopped for a treatment. The results of experiments areshown in FIG. 6.

[0049] In FIG. 6, plotted at a are results of experiments using dry air,at b are results of experiments using moistened air, at c are results ofexperiments using dry nitrogen gas, and at d are results of experimentsusing moistened nitrogen gas. As seen in this figure, as compared witheffects in a dry state, the same gas can reduce the contact angle morequickly when it is moistened state. Comparing with air, nitrogen gas ismore effecting in minimizing the contact angle quickly. When actuallywashing substrates 10, the transfer speed of the substrates 10 by theroller conveyer 11 is determined depending upon the size of the lamphouse 12. For example, in a process using moistened nitrogen gas and alamp house 12 measuring 450 mm in length in the substrate transferdirection, it suffices to transfer substrates at a speed of 30 mm/secand to irradiate same with ultraviolet light for a time duration ofapproximately 15 seconds to attain an initial objective of thetreatment.

[0050] The results of experiments show that the wettability can beimproved more quickly and in an assured manner particularly whenmoistened nitrogen gas is feed to a substrate 10. In addition, organiccontaminants on substrate surfaces can be decomposed smoothly andreliably into volatile forms not only through oxidative reactions butalso through reducing reactions. Accordingly, it is most advantageous ina case where substrates 10 need to be processed on an industrial scale.While substrates 10 are sent into the chamber 14 successively at apredetermined speed, the water vapor in the moistened nitrogen gas isconstantly maintained in a floating state within the entire inner spaceof the chamber 14. Threfore, the substrates as a whole can be wahsedclean and improved in wettability effciently in an assured manner.

[0051] Now, turning to FIG. 7, there is shown a third embodiment of thepresent invention. In this particularly embodiment, the processingapparatus includes a lamp house 212 with discharge lamps 1 and aprocessing chamber 214 for dry-washing or other surface treatment,similarly to the foregoing first embodiment. A substrate 10 which istransferred on a roller conveyer 11 is admitted into the changer 214through an entrance opening 214 a to receive a dry-washing treatmentsimilarly under irradiation of ultraviolet light from the dischargelamps 1 before being further sent forward to a next treating stagethrough an exit opening 214 b. A nitrogen gas feed pipe 213 is connectedto the lamp house 212, while a moistened inert gas feed pipe 215 isconnected to the chamber 214. Further, an exhaust pipe 218 is connectedto the chamber 214 to forcibly discharge exhaust gases from the chamber214. These arrangements are substantially same as in the foregoing firstembodiment.

[0052] In this case, however, a reflector plate 200 is provided withinthe lamp house 212. By the reflector plates 200, the lamp house 212 isdivided into a lower room 212D with the discharge lamps 1 and an upperroom 212U in communication with the nitrogen gas feed pipe 213. Thereflector plate 200 itself is divided into a plural number of sections.Void portions in the reflector plate 200 provide dry nitrogen gas flowpassages from the upper room 212U to the lower room 212D. In case thereflector plate 200 is constituted by a single undivided body, gas flowpassages of this sort can be formed by punching slits or holes therein.

[0053] The lower side of the reflector plate 200 on the side of thelower room 212D is mirror-finished or coated with a reflecting film toprovide a total reflection surface. Therefore, of the ultraviolet lightwhich is emitted from the discharge lamps 1, upward components aresubstantially totally reflected off the reflector plate 200 in downwarddirections to irradiate the substrate 10. The void portions in thereflector plate 200, that is, the dry nitrogen gas flow passages arelocated substantially immediately above the discharge lamps 1. Naemly,the reflector plate 200 does not exist immediately above the dischargelamps 1 because reflected ultraviolet light from these positions wouldbe blocked by the discharge lamps 1 without reaching the substrate 10.It follows that almost all of the ultraviolet light, which is irradiatedby the discharge lamps 1, contributes to the dry-washing of thesubstrate 10 without losses. In this regard, if desired, the efficiencyof ultraviolet light irradiation can be improved all the more by coatinga reflecting film on or mirror-finishing the entire inner wall surfacesof the lamp house 212.

[0054] Further, by the reflector plate 200, the lamp house 212 ispartitioned into the upper room 212U and the lower room 212D.Accordingly, nitrogen gas which is supplied to the lamp house 212through the nitrogen gas feed pipe 213 once dwells in the upper room 212and then flows into the lower room 212D through the void portions whichare provided in a plural number of ditributed positions of the reflectorplate 200. As a consequence, the nitrogen gas flows into every part ofthe lower room 212D uniformly in flow rate and pressure. Especially,since a reflector plate portion which contains no void gap is locatedbeneath the inlet opening of the nitrogen gas feed pipe 213, nitrogengas from a single feed pipe is distributed uniformly to the entire spaceof the lower room 212D of the lamp house 212.

[0055] Further, the chamber 214 is provided with a partition plate 201in assocation with the roller conveyer 11. The partition plate 202 isprovided with openings to receive top portions of the respective rollersof the roller conveyer 11 which abut against the lower side of thesubstrate 10. However, the partition plate 303 itself is kept out ofcontact with the lower side of the substrate 10. The partition plate 202functions to suppress pressure fluctuations within the chamber 214 aswell as disturbance in the moistened nitrogen gas flow which mayotherwise occur as a substrate 10 is admitted into the chamber 214 orsent out of the chamber 214 through the exit opening 214 b.

[0056] In this instance, the partition plate 202 can be arranged tofunction also as a plate heater. If so arranged, each substrate 10 whichis transferred by the roller conveyer 11 can be heated in the chamber214 for the purpose of enhancing the efficiency and capacity of thedry-washing treatment all the more.

[0057] Illustrated in FIG. 8 is a fourth embodiment of the presentinvention. In this embodiment, a boundary is provided across an openingat the lower end of the lamp house 212 which is projected into thechamber 214, drawing a border between a dry nitrogen gas atmosphere inthe lamp house 212 and a moistened inert gas atmosphere in the chamber214. The boundary is formed by the use of a partition plate 202 of apredetermined thickness. The partition plate 202 is constituted, forexample, by a plate of honeycomb or grid-like structure which contains amultitude of fine passages across its thickness and in its entiresurface areas. Further, the partition plate is coated with a reflectingfilm, including inner surfaces of fine passages.

[0058] In this case, the dry nitrogen gas in the lamp house 212 ismaintained at a pressure level slightly higher than a gas pressurewithin the chamber 214. Therefore, a border is defined between the drynitrogen gas atmosphere in the lamp house 212 and the moistened inertgas atmosphere in the chamber 214, and the moistened inert gas in thechamber 214 is prevented from flowing into the lamp house 212. Besides,the partition plate 202 is provided with a multitude of fine passage andcoated with a reflecting film substantially on its entire surfaces asdescribed hereinbefore, the ultraviolet light rays from the dischargelamps can pass through the fine passages even if the thickness of thepartition plate 202 is increased to some extent. The ultraviolt lightrays are reflected on inner surfaces of the fine passages and therebyled into the chamber 214.

[0059] Furthermore, in place of the above-described partition plate, awindow pane 202 of an ultraviolet light transmitting material such asquartz glass or the like may be fitted in the lower opening of the lamphouse as in a fifth embodiment of the invention shown in FIG. 9. In thiscase, although dry nitrogen gas is supplied to the lamp house 212through a nitrogen gas feed pipe 213, there is no necessity for keepingthe supply of dry nitrogen gas because the lamp house 212 issubstantially in a closed state.

[0060] Any way, in the foregoing second to fifth embodiments, pressurechambers may be provided on the outer side of the entrance and exitopenings 214 a and 214 b of the chamber 214 in the same manner as in thefirst embodiment. The exhaust pipe 218 is not required in case suchpressure chambers are maintained at a negative pressure level.

[0061] Shown in FIG. 10 is a sixth embodiment of the present invention.In this embodiment, the processing apparatus is arranged to generatemoistened inert gas within a n upper chamber 30. In a manner similar tothe foregoing first embodiment, a lamp house 31 with one or a pluralnumber of discharge lamps 1 is provided over the chamber 30, and thelower end of the lamp house 31 opened to the latter. Further, a nitrogengas feed pipe 32 is connected to an upper portion of the lamp house 31,supplying dry nitrogen gas under a predetermined pressure to maintain anoxygen-free atmosphere therein.

[0062] The chamber 30 is arranged to circumvent the opening of the lamphouse 31 and to extend to the lower side of a roller conveyer 33 whichtransfers a substrate 10. Entrance and exit openings 31 a and 31 b forthe substrate 10 are opened in upstream and downstream ends of thechamber 30 respectively. The chamber 30 is filled with pure water up toa predetermined level to provide a water vessel 34 under the rollerconveyer 33. In addition to simply holding water, the water vessel 34 isrequired to constantly supply fresh pure water, and, for this purpose, awater feed pipe 35 and a water discharge pipe 36 are connected to thewater vessel 34. The other end of the water feed pipe 35 is connected toa water supply tank 37 which is located at a higher position than thewater vessel 34. Accordingly, pure water is supplied to the water vessel34 under pressure of water head. The water discharge pipe 36 is openedinto the tank 34 at a position of a predetermined level, so that waterin the vessel 34 is allowed to overflow into the water discharge pipe 36as soon as the water level rises up to the position of the waterdischarge pipe 36. Accordingly, the water surface level in the vessel 34is maintained constantly at a predetermined height.

[0063] In the drawing, indicated at 38 is a nitrogen gas feed pipe whichserves as an inert gas feed pipe. A fore end portion of this nitrogengas feed pipe 38 is immersed in pure water in the water vessel 34 over apredetermined length. The nitrogen gas feed pipe 38 is provided with alarge number of fine blow holes in its immersed fore end portion. Asnitrogen gas is supplied to the nitrogen gas feed pipe 38 under apredetermined pressure, bubbles of nitrogen gas are incessantlygenerated around the immersed fore end portion of the nitrogen gas feedpipe 38, and water vapor is generated to moisten the nitrogen gas as thebubbles climb up toward the water surface within the vessel 34. As aresult, the inner space over the water surface level of the pure watervessel 34 is put in an atmosphere of moistened nitrogen gas whichcontains water vapor.

[0064] Nitrogen gas may be supplied to the nitrogen gas feed pipe 38from a bomb or steel bottle. However, in the case of the embodimentshown in FIG. 10, nitrogen gas is supplied from inside of the chamber30. For this purpose, a circulating pipe 40 is connected to a wallportion of the chamber 30. The other end of the circulating pipe 40 isconnected to a pump 41 the delivering side of which is connected to thenitrogen gas feed pipe 38. Accordingly, upon actuating the pump 41,nitrogen gas in the chamber 30 is taken up into the circulating pipe 40and supplied to the nitrogen gas feed pipe 38. Further, connected to thechamber 30 is an exhaust pipe 42 which is provided with a pressurecontrol valve 43 within its length. Therefore, as soon as the internalpressure of the chamber 30 exceeds a preset value, excessive nitrogengas in the chamber 30 is discharged through the exhaust pipe 42 tomaintain the chamber 30 constantly at a predetermined pressure level.

[0065] With these arrangements, the inside of the lamp house 31 is putin a dry nitrogen gas atmosphere, while the inside of the chamber 30,except the lamp house 31, is put in a moistened nitrogen gas atmospherewhich conssits of nitrogen gas and water vapor and which issubstantially free of oxygen. By nitrogen gas which is supplied throughthe nitrogen gas feed pipe 38, the inside of the lamp house 31 ismaintained at a pressure level which is higher than the atomophericpressure. However, by way of an exhaust pipe 42 which is connected tothe chamber 30, the internal pressure of the chamber 30 is maintained ata level intermediate between the internal pressure of the lamp house 31and the atmospheric pressure. As a consequence, due to constant gasflows from the lamp house 31 into the chamber 30, the inside of the lamphouse 31 is maintained in a dry state, precluding possibilities of watervapor entering the lamp house 31. On the other hand, the chamber 30 ismaintained at a higher pressure level than the atmospheric pressure,there is no possibility of air entering the chamber 30 from outsidethrough entrance and exit openings 31 a and 31 b.

[0066] With the arrangements just described, the chamber 30 can befilled with moistened nitrogen gas which contains both nitrogen gas andwater vapor. Accordingly, as the discharge lamps 1 are lit on and asubstrate 10 on the roller conveyer 33 is advanced into the chamber 30,the surface of the substrate 10 is dry-washed by irradiation of shortwavelength ultraviolet light from the discharge lamps 1, which stripsand removes organic contaminants from the substrate surfaces, and at thesame time treated to have a smaller contact angle.

[0067] In this instance, when the substrate 10 comes face to face withthe lamp house 31, the moistened nitrogen gas forms a thin layer on thefront surface of the substrate. The thickness of the nitrogen gas layercan be adjusted by way of a pressure differential between the lamp house31 and the chamber 30. In this regard, the pressure differential can bemaintained constantly at a predetermined value by adjusting the controllevel of the pressure control valve 43 in the nitrogen gas feed pipe 42which is connected to the chamber 30, while supplying nitrogen gas tothe lamp house 31 through the nitrogen gas feed pipe 32 under a constantpressure.

[0068] If the thickness of a layer of the moistened nitrogen gas, i.e.,a layer of a mixture of nitrogen gas and water vapor, between thedischarge lamps 1 and the substrate 10 is increased to an excessivedegree, the absorption of ultraviolet light by the moistened gas layeris increased correspondingly to lessen the effects on the substratesurface. On the contrary, in case the moistened nitrogen gas layer istoo thin, the amount of decomposition products becomes smaller.Accordingly, the effciency of dry-washing of substrate surfaces can beenhanced by setting an appropriate control value for the pressurecontrol valve 43. Similar effects can be attained by controlling theflow rate of nitrogen gas through the nitrogen gas feed pipe 32 alongwith the flow rate of water vapor-containing nitrogen gas through theexhaust pipe 42.

[0069] In this instance, as shown in FIG. 11, a pane of quartz glass orother ultraviolet light transmitting glass may be fitted in the loweropen side of the lamp house 31 thereby to hold an inert gas in the lamphouse 31 a sealed state and to prevent its leaks to the outside.

[0070] Further, also in the case of the sixth embodiment shown in FIG.10 and the seventh embodiment shown in FIG. 11, it is desirable for thelamp house 31 to include a function of reflecting back upward componentsof ultraviolet light toward the substrate. More particularly, areflector plate 45 is located above the discharge lamps 1 in the case ofthe embodiment of FIG. 10, while a reflecting film 46 is coated onentire inner surfaces of the lamp house 31 in the case of the embodimentof FIG. 11.

[0071] As described hereinbefore, no matter whether moistened inert gasis supplied to the lamp house or it is generated within the lamp house,organic contaminants are removed from an irradiated surface of asubstrate 10 and at the same time the contact angle of the substratesurface is minimized by a dry-washing treatment in the apparatus shownin the first to seventh embodiments of the invention. After adry-washing treatment, the substrate 10 is further processed asschematically shown in FIG. 12.

[0072] In FIG. 12, indicated at 50 is the above-described dry-washingstage, which in this particular case is followed by a wet-washing stage51 and a drying stage 52 to clean up the surface of each substrate 10completely.

[0073] In the wet-washing stage 51, inorganic contaminants on thesurface of a substrate 10 are removed by a shower of ultrasonicallyvibrated pure water which is spurted out from a shower unit 51 a. Inthis regard, the wet-drying stage 51 may be arranged to include awet-washing treatment other than wet-washing in a pure water shower, forexample, a treatment such as scrubbing by the use of brushes or dippingin an ultrasound water bath singly or in combination. By the end of thewet-washing operation, organic as well as inorganic contaminants arealmost completely removed from the surface of the substrate 10 to bringthe latter to an extremely clean state. Further, as for a drying systemsuitable for use in the drying stage 52, there may be employed, forexample, a spin-drier or an air knife drier which is provided with anair knife nozzle 52 a as shown in the drawing for drying substrates byair knife effects. Thus, substrates 10 are washed and dried completelythrough the processing line as described above.

[0074] Alternatively, the dry-washing may be carried out in a stagesubsequent to the wet-washing and drying stages. For instance, in a casewhere the dry-washing is carried out as a pretreatment prior toapplication of a liquid developer, firstly contaminant substances areremoved from surface of a substrate 10 by wet-washing and then oncedried before sending the substrate to dry-washing to improve its surfaceconditions, particularly, to improve its contact angle. The dry-washingtreatment makes it possible to apply a liquid developer or the likeuniformly on the substrate surface in a subsequent stage.

What is claimed is:
 1. An apparatus for treating substrate surfaces,comprising: a lamp house located over a substrate transfer path and faceto face with a treating surface of a substrate being transferred alongsaid transfer path by a conveyer means; a dielectric barrier dischargelamp fixedly mounted in said lamp house to irradiate ultravilot lighttoward said substrate; and a moistened inert gas generating meansadapted to supply a water vapor-containing moistened inert gas to aspace between said substrate and said dielectric barrier discharge lamp;producing a reducing active member [H.] and an oxidative active member[.OH] by irradiating said moistened inert gas with ultraviolet lightfrom said dielectric barrier discharge lamp.
 2. An apparatus fortreating substrate surfaces as defined in claim 1, wherein saidsubstrate is a plate of glass, synthetic resin, ceramics or metal, or acomposite plate of such materials.
 3. An apparatus for treatingsubstrate surfaces as defined in claim 1, wherein said moistened inertgas is a mixed fluid of pure water vapor and nitrogen gas.
 4. Anapparatus for treating substrate surfaces as defined in claim 1, whereinsaid lamp house is provided within a chamber holding a moistened inertgas atmosphere therein, and provided with entrance and exit openings atupstream and downstream ends thereof for said substrate.
 5. An apparatusfor treating substrate surfaces as defined in claim 4, wherein saidchamber is adapted to hold a substantially oxygen-free atmospheretherein.
 6. An apparatus for treating substrate surfaces as defined inclaim 4, wherein said conveyer means is constituted by a roller conveyerextending into and across said chamber.
 7. An apparatus for treatingsubstrate surfaces as defined in claim 6, wherein said chamber includesa partition plate located beneath a substrate transfer surface of saidroller conveyer and out of contact with said substrate, said partitionplate being provided with slots to receive top portions of rollers ofsaid roller conveyer to be brought into abutting engagement with saidsubstrate.
 8. An apparatus for treating substrate surfaces as defined inclaim 7, wherein said partition plate is constituted by a heater plate.9. An apparatus for treating substrate surfaces as defined in claim 4,wherein said lamp house is opened into said chamber, and an inert gasfeed means is connected to said lamp house.
 10. An apparatus fortreating substrate surfaces as defined in claim 9, wherein said inertgas feed means is constituted by an inert gas feed pipe connected to atop side of said lamp house, and a reflector plate is provided over saiddielectric barrier discharge lamp in said lamp house to reflect upwardcomponents of said ultraviolet light, said reflector plate being solocated as to divide said lamp house into an upper room in communicationwith said inert gas feed pipe and a lower room accommodating saiddielectric barrier discharge lamp, said reflector plate containing voidportions to circulate said inert gas from said upper room to said lowerroom.
 11. An apparatus for treating substrate surfaces as defined inclaim 9, wherein said moistened inert gas generating means includes amoistened inert gas feed means connected to said chamber and adapted tosupply a water vapor-containing moistened inert gas toward said treatingsurface of said substrate.
 12. An apparatus for treating substratesurfaces as defined in claim 11, wherein said moistened inert gas feedmeans is adapted to supply said moistened inert gas toward a positionforward of said substrate advancing toward the said lamp house.
 13. Anapparatus for treating substrate surfaces as defined in claim 10,wherein said inert gas feed means is adapted to supply said inert gas tosaid lamp house under a higher pressure than said moistened inert gassupplied by said moistened inert gas feed means.
 14. An apparatus fortreating substrate surfaces as defined in claim 10, wherein saidmoistened inert gas feed means is constituted by a pure water tank, anda nitrogen gas feed pipe having a multitude of fine gas blow holes in afore end portion which is submerged in said pure water tank to generatea moistened inert gas.
 15. An apparatus for treating substrate surfacesas defined in claim 14, further comprising a moistened inert gasinduction pipe connecting said pure water tank to a mixing container toadjust concentration of water vapor in said moistened inert gas fromsaid pure water tank, said mixing container being connected to saidchamber through said moistened inert gas feed pipe.
 16. An apparatus fortreating substrate surfaces as defined in claim 15, further comprisingan exhaust pipe connected to said chamber.
 17. An apparatus for treatingsubstrate surfaces as defined in claim 4, wherein said moistened inertgas generating means is constituted by a pure water vessel, which purewater vessel being open at a top end located face to face with said lamphouse and adapted to hold pure water therein, and an inert gas feedmeans located in said pure water vessel and provided with a multitude ofinert gas blow holes.
 18. An apparatus for treating substrate surfacesas defined in claim 17, wherein a roller conveyer of said substrateconveyer means is located acrosss said chamber, and said pure watervessel is located on the lower side of said roller conveyer.
 19. Anapparatus for treating substrate surfaces as defined in claim 17,wherein said lamp house is opened toward a front surface of saidsubstrate being transferred along said path of transfer, and said inertgas feed means is connected to said lamp house.
 20. An apparatus fortreating substrate surfaces as defined in claim 17, wherein said inertgas feed means includes an inert gas feed pipe immersed in pure water insaid pure water vessel and provided with a multitude of gas blow holes.21. An apparatus for treating substrate surfaces as defined in claim 17,further comprising a water feed pipe connected to said pure water vesselat one end thereof, and an overflow type water discharge pipe opened ata predetermined height of said pure water vessel.
 22. An apparatus fortreating substrate surfaces as defined in claim 21, wherein the otherend of said water feed pipe is connected to a water tank located in ahigher position than said pure water vessel.
 23. An apparatus fortreating substrate surfaces as defined in claim 17, further comprisingan exhaust pipe connected at one end to said chamber and at the otherend to a suction side of a pump, the delivery side of which pump beingconnected to said inert gas feed means.
 24. An apparatus for treatingsubstrate surfaces as defined in claim 4, wherein said lamp house ishermetically closed by an ultraviolet light transmitting window providedon a side facing toward said substrate.
 25. An apparatus for treatingsubstrate surfaces as defined in claim 24, wherein said window is panedwith quartz glass.
 26. An apparatus for treating substrate surfaces asdefined in claim 9, wherein said lamp house is provided with a partitionmember of a predetermined thickness on a side facing toward saidsubstrate, said partition member being provided with a multitude of fineholes across said thickness, and a reflecting film coated on entiresurfaces of said partition member including inner surfaces of said fineholes.
 27. An apparatus for treating substrate surfaces as defined inclaim 1, wherein inner surfaces of said lamp house is coated with areflecting film to reflect off ultraviolt light.
 28. A method fortreating substrate surfaces, comprising the steps of: placing asubstrate in a mixed atmosphere of an inert gas and water vapor underirradiation of ultraviolet light from a dielectric barrier dischargelamp, thereby splitting water vapor into a reducing active member [H.]and an oxidative active member [.OH]; and letting said reducing andoxidative active members [H.] and [.OH] contact with a surface of saidsubstrate to be treated.
 29. A method for treating substrate surfaces,comprising the steps of: horizontally transferring a substrate into amixed atmosphere of an inert gas and water vapor under irradiation ofultraviolet light from a dielectric barrier discharge lamp, therebydecomposing organic substances deposited on a surface of said substrateand at the same time splitting water vapor into a reducing active member[H.] and an oxidative active member [.OH]; and subjecting said reducingand oxidative active members [H.] and [.OH] to reactions withdecomposition products of said organic substances.
 30. A method fortreating substrate surfaces, comprising the steps of: horizontallytransferring a substrate into a mixed atmosphere of an inert gas andwater vapor under irradiation of ultraviolet light from a dielectricbarrier discharge lamp, thereby decomposing organic substances depositedon a surface of said substrate and at the same time splitting watervapor into a reducing active member [H.] and an oxidative active member[.OH]; dry-washing and minimizing contact angle of a surface of saidsubstrate by subjecting said reducing and oxidative active members [H.]and [.OH] to reactions with decomposition products of said organicsubstances; wet-washing siad substrate by supplying a wash liquidthereto; and drying said substrate.